1. Field of the Invention
The present invention relates to an ATM cell compression device and ATM cell recovery (decompression) device, ATM cell compression recovery (decompression) device, ATM cell compression recovery system, and ATM cell compression recovery method that are suitable for use in the enhancement of data transmission efficiency in the ATM (Asynchronous Transfer Mode) network to which the ATM system is applied.
2. Description of Related Art
In a data transmission by the ATM system, the data are not transmitted in a fixed timing as in a data transmission by the conventional STM (Synchronous Transfer Mode) system, but are transmitted in an arbitrary timing by treating each data cell as a fixed length, to which the identification information of a destination is attached.
Accordingly, in the data transmission by the ATM system, when there is a vacant band without data transmitted, it is possible to utilize the band with efficiency by allocating arbitrary data according to the contract of a service quality.
Therefore, generally in a certain band are multiplexed the cells of various service categories from a plurality of end users. Accordingly, the ATM system is suitable for providing multimedia services that are different in the transmission speeds.
Further, the service category by the ATM system includes CBR, rtVBR, nrtVBR, ABR, UBR, etc., and these service categories include the priorities of securing the band.
However, in a lower priority service area, the cells can be nullified in case the band cannot be secured. In such a case, the service quality cannot be maintained, which is a problem.
That is, in a lower priority service category, in case there is not a vacancy in the band, data are queued in a buffer in the ATM switch, and the data are transmitted when the band is secured. In the UBR of a low priority, for example, since this UBR is a service in which the band securement is not provided, when the band for transmission is not available and the cells whose quantity exceeds the capacity of the foregoing buffer are queued, the cells are subjected to nullification, and thus the service quality will be lowered.
Accordingly, in the conventional ATM network, end users transmit data compressed in the upper application layer to thereby reduce cells that are nullified, thus lowering the cell loss rate.
However, due to the recent widespread of the internet and advancement of peripheral hardware, the data transmitted by end users are anticipated to increase, and it is expected even more strongly to use the band effectively in the ATM network where these data are multiplexed.
Therefore, it is preferable to compress the data not only in the upper application layer by the end users, but in the ATM nodes being the repeating points of the ATM network; however, the conventional ATM network has not ever performed the compression of data in the lower ATM layer, or the recovery of the compressed data in the ATM layer.
The present invention has been made in view of the foregoing problems, and it is therefore an object to provide an ATM cell compression device and ATM cell recovery device, ATM cell compression recovery device, ATM cell compression recovery system, and ATM cell compression recovery method, wherein the data compression and recovery is performed in the ATM layer so that the cell loss rate can be lowered to maintain and enhance the service quality and the congestion of transmission lines can be reduced.
In order to accomplish the foregoing object, the ATM cell compression device of the invention comprises a compression object cell determination unit that determines whether an inputted ATM cell is a compression object cell, and a compressed cell production unit that, when the compression object cell determination unit determines that the ATM cell is a compression object cell, applies a compression processing to the ATM cell in an ATM layer to produce a compressed cell.
Concretely, the ATM cell compression device of the invention comprises a compression pattern sample storage unit that stores a compression pattern sample of a compression object cell, wherein the compression object cell determination unit determines whether the ATM cell is a compression object cell on the basis of the compression pattern sample stored in the compression pattern sample storage unit.
Here, the compression pattern sample storage unit may be constructed so as to modify the compression pattern sample stored in the compression pattern sample storage unit.
In this case, it is needed to construct such that the compression pattern sample storage unit updates the compression pattern sample of a plurality of compression pattern samples stored in the compression pattern sample storage unit, serving a pattern sample having a high coincidence with inputted ATM cells as a compression pattern sample having a high priority.
Further, the ATM cell compression device of the invention may be comprised of a transmission cell storage unit that stores an ATM cell to be transmitted, and a transmission cell monitor unit that requests the compressed cell production unit to produce a compressed cell, when the ATM cell in the transmission cell storage unit which is to be transmitted comes into a state of waiting.
Thus, according to the ATM cell compression device of the invention, the compression processing can be applied to an inputted ATM cell to produce a compressed cell; and therefore, the ATM cell quantity transmitted through the ATM network can be reduced and the bands can be utilized by the cell compression in the different communication bands. Therefore, the cell loss rate can be lowered and the service quality can be maintained and enhanced; and since the retransmission processing caused by the cells being lost can be reduced, the congestion of the transmission lines can be reduced, which is advantageous.
And, according to the ATM cell compression device of the invention, the compression pattern sample can be modified which is stored in the compression pattern sample storage unit; and therefore, the types of the pattern samples can be optimized to enhance the patternizing rate, which is advantageous.
Further, the ATM cell recovery device is provided with a compressed cell determination unit that determines whether an ATM cell inputted from an opposite ATM cell compression device is a compressed cell, and a cell recovery unit that, when the compressed cell determination unit determines that the ATM cell is a compressed cell, applies a recovery processing to the ATM cell in an ATM layer to recover the compressed cell into the original ATM cell.
Concretely, the ATM cell recovery device of the invention comprises a recovery pattern sample storage unit that stores a recovery pattern sample of an original ATM cell corresponding to a compressed cell, and when the compressed cell determination unit determines that the ATM cell is a compressed cell, the cell recovery unit recovers the compressed cell into the original ATM cell on the basis of the recovery pattern sample stored in the recovery pattern sample storage unit.
Here, the recovery pattern sample storage unit may be constructed so as to modify the recovery pattern sample stored in the recovery pattern sample storage unit.
In this case, it is needed to construct such that the recovery pattern sample storage unit updates the recovery pattern sample of a plurality of recovery pattern samples stored in the recovery pattern sample storage unit, serving a pattern sample having a high coincidence with the original ATM cell corresponding to an inputted compressed cell as a recovery pattern sample having a high priority.
Thus, according to the ATM cell recovery device of the invention, the recovery processing can be applied to a compressed cell produced by the compression processing that has been applied in the ATM layer, and the compressed cell can be recovered into the original ATM cell; and therefore, the ATM cell quantity transmitted through the ATM network can be reduced and the bands can be utilized by the cell compression in the different communication bands. Therefore, the cell loss rate can be lowered and the service quality can be maintained and enhanced; and since the retransmission processing caused by the cells being lost can be reduced, the congestion of the transmission lines can be reduced, which is advantageous.
And, according to the ATM cell recovery device of the invention, the recovery pattern sample stored in the recovery pattern sample storage unit can be modified to follow the modification contents of the compression pattern sample; and therefore, the types of the pattern samples can be optimized to enhance the patternizing rate, which is advantageous.
Further, the ATM cell compression recovery device of the invention comprises an ATM cell recovery device, a switch device, and an ATM cell compression device. The ATM cell recovery device includes a compressed cell determination unit that determines whether an ATM cell inputted from an opposite ATM cell compression device through a transmission line is a compressed cell, and a cell recovery unit that, when the compressed cell determination unit determines that the ATM cell is a compressed cell, applies a recovery processing to the ATM cell in an ATM layer to recover the compressed cell into an original ATM cell. The switch device applies a switching processing to an ATM cell recovered by the ATM cell recovery device. And, the ATM cell compression device includes a compression object cell determination unit that determines whether an ATM cell outputted from the switch device toward an identical path is a compression object cell, and a compressed cell production unit that, when the compression object cell determination unit determines that the ATM cell is a compression object cell, applies a compression processing to the ATM cell in an ATM layer to produce a compressed cell.
Concretely, in the ATM cell compression recovery device of the invention, the ATM cell recovery device comprises a recovery pattern sample storage unit that stores a recovery pattern sample of an original ATM cell corresponding to a compressed cell, and when the compressed cell determination unit determines that the ATM cell is a compressed cell, the cell recovery unit recovers the compressed cell into the original ATM cell on the basis of the recovery pattern sample stored in the recovery pattern sample storage unit. And accordingly, the ATM cell compression device comprises a compression pattern sample storage unit that stores a compression pattern sample of a compression object cell, and the compression object cell determination unit determines whether the ATM cell is a compression object cell on the basis of the compression pattern sample stored in the compression pattern sample storage unit.
Further, the ATM cell compression recovery device of the invention comprises an ATM cell compression device and an ATM cell recovery device. The ATM cell compression device includes a compression object cell determination unit that determines whether an inputted ATM cell is a compression object cell, and a compressed cell production unit that, when the compression object cell determination unit determines that the ATM cell is a compression object cell, applies a compression processing to the ATM cell in an ATM layer to produce a compressed cell. And, the ATM cell recovery device includes a compressed cell determination unit that determines whether an ATM cell inputted from an opposite ATM cell compression device through a transmission line is a compressed cell, and a cell recovery unit that, when the compressed cell determination unit determines that the ATM cell is a compressed cell, applies a recovery processing to the ATM cell in an ATM layer to recover the compressed cell into the original ATM cell.
Concretely, in the ATM cell compression recovery device of the invention, the ATM cell compression device comprises a compression pattern sample storage unit that stores a compression pattern sample of a compression object cell, and the compression object cell determination unit determines whether the ATM cell is a compression object cell on the basis of the compression pattern sample stored in the compression pattern sample storage unit. And accordingly, the ATM cell recovery device comprises a recovery pattern sample storage unit that stores a recovery pattern sample of an original ATM cell corresponding to a compressed cell, and when the compressed cell determination unit determines that the ATM cell is a compressed cell, the cell recovery unit recovers the compressed cell into the original ATM cell on the basis of the recovery pattern sample stored in the recovery pattern sample storage unit.
Further, the ATM cell compression recovery system of the invention comprises an ATM cell compression device and an ATM cell recovery device. The ATM cell compression device includes a compression object cell determination unit that determines whether an inputted ATM cell is a compression object cell, and a compressed cell production unit that, when the compression object cell determination unit determines that the ATM cell is a compression object cell, applies a compression processing to the ATM cell in an ATM layer to produce a compressed cell. And, the ATM cell recovery device includes a compressed cell determination unit that determines whether an ATM cell inputted from the ATM cell compression device through a transmission line is a compressed cell, and a cell recovery unit that, when the compressed cell determination unit determines that the ATM cell is a compressed cell, applies a recovery processing to the ATM cell in an ATM layer to recover the compressed cell into the original ATM cell.
Concretely, in the ATM cell compression recovery system of the invention, the ATM cell compression device comprises a compression pattern sample storage unit that stores a compression pattern sample of a compression object cell, and the compression object cell determination unit determines whether the ATM cell is a compression object cell on the basis of the compression pattern sample stored in the compression pattern sample storage unit. And accordingly, the ATM cell recovery device comprises a recovery pattern sample storage unit that stores a recovery pattern sample of an original ATM cell corresponding to a compressed cell, and when the compressed cell determination unit determines that the ATM cell is a compressed cell, the cell recovery unit recovers the compressed cell into the original ATM cell on the basis of the recovery pattern sample stored in the recovery pattern sample storage unit.
In this case, the compression pattern sample storage unit may be constructed so as to modify the compression pattern sample stored in the compression pattern sample storage unit. And, the recovery pattern sample storage unit may be constructed so as to modify the recovery pattern sample stored in the recovery pattern sample storage unit, while following the modification contents of the compression pattern sample stored in the compression pattern sample storage unit.
Further, the ATM cell compression recovery method of the invention comprises an ATM cell compression step and an ATM cell recovery step. The ATM cell compression step contains a compression object cell determination step that determines whether an inputted ATM cell is a compression object cell, and a compressed cell production step that, when the compression object cell determination step determines that the ATM cell is a compression object cell, applies a compression processing to the ATM cell in an ATM layer to produce a compressed cell. And accordingly, the ATM cell recovery step contains a compressed cell determination step that determines whether an ATM cell produced by the ATM cell compression step transmitted through a transmission line is a compressed cell, and a cell recovery step that, when the compressed cell determination step determines that the ATM cell is a compressed cell, applies a recovery processing to the ATM cell in an ATM layer to recover the compressed cell into the original ATM cell.
In this case, the processings in the ATM cell compression step and the ATM cell recovery step may be executed in each ATM service category.
Further, the compression object cell determination step, the compressed cell production step, the compressed cell determination step, and the cell recovery step of the ATM cell compression recovery method may be constructed as follows. The compression object cell determination step determines whether the ATM cell is a compression object cell on the basis of the compression pattern sample. The compressed cell production step includes, when the compression object cell determination step determines that an ATM cell subsequent to the ATM cell determined to be the compression object cell is determined not to be a compression object cell, the compression pattern sample information corresponding to the ATM cell determined to be the compression object cell in the subsequent ATM cell to thereby produce the compressed cell. The compressed cell determination step determines whether an ATM cell produced by the ATM cell compression step transmitted through the transmission line is a compressed cell, on the basis of whether the concerned ATM cell contains the compression pattern sample information. And, when the compressed cell determination step determines that the ATM cell is a compressed cell, the cell recovery step recovers the compressed cell into the original ATM cell on the basis of the recovery pattern sample of the original ATM cell corresponding to the compression pattern sample information.
Thus, according to the ATM cell compression recovery device, the ATM cell compression recovery system, and the ATM cell compression recovery method, the compression processing can be applied to an inputted ATM cell in the ATM layer to produce a compressed cell, and the recovery processing can be applied to the compressed cell thus produced in the ATM layer to recover the original ATM cell; and therefore, the ATM cell quantity transmitted through the ATM network can be reduced and the bands can be utilized by the cell compression in the different communication bands. Therefore, the cell loss rate can be lowered and the service quality can be maintained and enhanced; and since the retransmission processing caused by the cells being lost can be reduced, the congestion of the transmission lines can be reduced, which is advantageous.
And, according to the ATM cell compression recovery system of the invention, the compression pattern sample stored in the compression pattern sample storage unit can be modified on one side, and the recovery pattern sample stored in the recovery pattern sample storage unit can be modified to follow the modification contents of the compression pattern sample; and therefore, the types of the pattern samples can be optimized to enhance the patternizing rate, which is advantageous.